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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An Asset Management Framework Based on Field Performance of Pavement Markings

Madiri, Sam 2010 May 1900 (has links)
Performance-based asset management provides a strategic framework for managing transportation infrastructure to improve existing procedures for resource allocation. The importance of comprehensive management of pavement marking assets not only results in monetary benefits to the agencies but also complements other management systems in providing safer driving conditions. A majority of research concerned with pavement markings addresses installation, performance, maintenance, and economic evaluation. Although agencies have developed guides and manuals on these subjects, they had difficulties in practical implementation. The purpose of this study was to address the issues that were identified in the practical implementation of analytical and information tools of asset management practice in the field of pavement markings. Problems of limited variable data, censored data and uncertainty in field evaluation and retroreflectivity based prediction were addressed by adopting statistical techniques. Sectional assessment and management methods were proposed as a part of a practical restriping methodology. An information tool was developed in a geographic information system (GIS) environment as an application. Retroreflectivity was the only performance measure on which the analysis and application was carried out. Two case studies were conducted, one for statistical techniques with retroreflectivity data collected by the National Transportation Product Evaluation Program (NTPEP) on U.S. Highway 78 westbound, Lee County, Mississippi. The other for application with retroreflectivity data collected using mobile retroreflectivity unit (MRU) on FM 57, Fisher County, Texas. This research effort provides a framework for an agency in developing a pavement marking management program to maintain good visibility of markings. It also provides a basis for further research in building an integrated asset management system based on other transportation assets.
2

Experimental Investigation of Typical Aircraft Field Performance Versus Predicted Performance Targets

January 2017 (has links)
abstract: This thesis explores the human factors effects pilots have when controlling the aircraft during the takeoff phase of flight. These variables come into play in the transitory phase from ground roll to flight, and in the initiation of procedures to abort a takeoff during the ground run. The FAA provides regulations for manufacturers and operators to follow, ensuring safe manufacture of aircraft and pilots that fly without endangering the passengers; however, details regarding accounting of piloting variability are lacking. Creation of a numerical simulation allowed for the controlled variation of isolated piloting procedures in order to evaluate effects on field performance. Reduced rotation rates and delayed reaction times were found to cause significant increases in field length requirements over values published in the AFM. A pilot survey was conducted to evaluate common practices for line pilots in the field, which revealed minimum regulatory compliance is exercised with little to no feedback on runway length requirements. Finally, observation of pilots training in a CRJ-200 FTD gathered extensive information on typical piloting timings in the cockpit. AEO and OEI takeoffs were observed, as well as RTOs. Pilots showed large variability in procedures and timings resulting in significant inconsistency in runway distances used as well as V-speed compliance. The observed effects from pilot timing latency correlated with the numerical simulation increased field length outputs. Variability in piloting procedures results in erratic field performance that deviates from AFM published values that invite disaster in an aircraft operating near its field performance limitations. / Dissertation/Thesis / Masters Thesis Human Systems Engineering 2017
3

The Doghouse Plot: History, Construction Techniques, and Application

January 2017 (has links)
abstract: The Doghouse Plot visually represents an aircraft’s performance during combined turn-climb maneuvers. The Doghouse Plot completely describes the turn-climb capability of an aircraft; a single plot demonstrates the relationship between climb performance, turn rate, turn radius, stall margin, and bank angle. Using NASA legacy codes, Empirical Drag Estimation Technique (EDET) and Numerical Propulsion System Simulation (NPSS), it is possible to reverse engineer sufficient basis data for commercial and military aircraft to construct Doghouse Plots. Engineers and operators can then use these to assess their aircraft’s full performance envelope. The insight gained from these plots can broaden the understanding of an aircraft’s performance and, in turn, broaden the operational scope of some aircraft that would otherwise be limited by the simplifications found in their Airplane Flight Manuals (AFM). More importantly, these plots can build on the current standards of obstacle avoidance and expose risks in operation. / Dissertation/Thesis / Masters Thesis Aerospace Engineering 2017
4

Det sportsliga resultatets påverkan på sponsorskap : En explorativ studie om sponsorgivarens inställning till det sportsliga resultatets påverkan på sponsorskapet

Fredholm Lundgren, Madeleine, Berggren, Martin January 2020 (has links)
Sponsorship is one of the most effective marketing strategies for corporations to communicate with their target audience as well as improving their brand. The most common sponsorship is sports related, despite this there is a lack of research regarding the on-field performance effect on sponsorship. The aim of this study is to investigate the importance of the on-field performances and their effects on the team’s sponsorships.   The following marketing model and marketing theories have been used: A-ERIC Model, Brand Equity and Brand Image Transfer. All of these have previously been used in different scientific studies and has, because of this, been chosen to act as the foundation of this study. A qualitative data collecting method has been used in this study to be able to work towards the aim of it and fulfil the ambition to answer the scientific questions asked. With an interview guide as support, five semi structured interviews have been created and completed.   The result of this study show that the on-field performances has an indirect effect on the sponsorships. Poor performances can result in worse exposure for the sponsorships and affect them negatively. On the other hand, the fact that sponsorgiver show their support can give them a positive effect because they appear loyal to the sport organization. It also became clear that communication had a major impact and depending on how the sport organization chooses to communicate its goals, it will determine the expectations for sponsorship. Additionally, the study has also shown that communication has a big effect on how important the on-field performances are for the sponsors. The communication between the sponsorgiver and sponsortaker, also has a big effect on how important the on-field performance is for the sponsor.
5

Field performance of corrugated plastic pipes under simulated high soil cover

Fernando, Mihindukulasooriya E. R. January 1992 (has links)
No description available.
6

Exploiting the genetic diversity of rapeseed (Brassica napus L.) root morphology to improve nitrogen acquisition from soil

Louvieaux, Julien 12 October 2020 (has links) (PDF)
Nitrogen (N) is a central nutrient in cropping systems. However, a considerable N fraction is lost through runoffs and leaching with detrimental consequences for environment and controversial effects on human health. Increasing the plant N uptake by optimizing the degree of root branching for exploring a larger soil volume in search of the mobile nitrate resource may contribute to limit soil leaching and subsequently to rely more efficiently on the soil mineralization and fertilizer inputs. Rapeseed (Brassica napus L.) is a major oil crop that highly depends on N fertilization. This doctoral thesis aims at exploring the diversity of root morphology in recently selected cultivars and in a large set of rapeseed inbred lines, and at understanding the genetic control on root morphology and how it is impacted by N nutrition.Firstly, a panel of twenty-eight European recently selected cultivars of winter oilseed rape were tested in laboratory and field conditions. Upon hydroponic culture, these hybrids showed a great diversity for biomass production and root morphological traits. Differences in root and shoot dry biomasses and lateral root length were mainly explained by the genotype, while differences in primary root length by the nutrition. The cultivars were tested in a pluriannual field trial. The observed variation for yield and seed quality traits attributed to the genotype was more important than the year or the genotype x year interaction effects. The total root length measured in laboratory could predict the proportion of nitrogen taken-up from the field and reallocated to the seeds. The genetic interrelationship between cultivars, established with polymorphic markers, indicated a very narrow genetic base. Positive correlations were found between the genetic distance measures, root morphological trait distances during nitrogen depletion conditions, and agronomic performance. Secondly, three cultivars previously selected from a root morphology screen at a young developmental stage were field tested with two nitrogen applications. The purpose was to examine the relationship between root morphology and Nitrogen Uptake Efficiency (NUpE) and to test the predictiveness of canopy optical indices for seed quality and yield. A tube-rhizotron system was used to incorporate below-ground root growth information. One-meter length clear tubes were installed in soil at an angle of 45°. The root development was followed with a camera at key growth stages in autumn (leaf development) and spring (stem elongation and flowering). Autumn was a critical time window to observe the root development and exploration in deeper horizons (36-48 cm) was faster without any fertilization treatment. Analysis of the rhizotron images was challenging and it was not possible to clearly discriminate between cultivars. Canopy reflectance and leaf optical indices were measured with proximal sensors. The Normalized Difference Vegetation Index (NDVI) was a positive indicator of biomass and seed yield while the Nitrogen Balance Index (NBI) was a positive indicator of above-ground biomass N concentration at flowering and seed N concentration at harvest.Thirdly, the natural variability offered by a diversity set of 392 inbred lines was screened to apprehend the genetic control of root morphology in rapeseed and how it is impacted by nitrogen nutrition. Seedlings grew hydroponically with low (0.2 mM) or elevated (5 mM) nitrate supplies. Low nitrate supply triggered the primary root and lateral root growth, while elevated supply promoted shoot biomass production. A considerable variation degree in the root morphological traits was observed across the diversity set, and there was no trade-off between abundant lateral root branching and shoot biomass production. Root traits were mainly dependent on the genotype and highly heritable. A genome wide association study identified some genomic regions associated with biomass production and root morphological traits. A total of fifty-nine QTLs were identified and thirty of them were integrated into seven clusters on chromosomes A01 and C07. Some candidate genes were identified with Arabidopsis orthologs related to root growth and development, nitrogen nutrition or hormone regulation.This study provides promising routes for redesigning the root system architecture by uncovering nitrogen-interactive genomic regions shaping root morphology. A perspective is to develop genetic markers associated with root morphological traits that could be used for assisted breeding. / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished
7

Advances in Thermal Insulation : Vacuum Insulation Panels and Thermal Efficiency to Reduce Energy Usage in Buildings

Thorsell, Thomas January 2012 (has links)
We are coming to realize that there is an urgent need to reduce energy usage in buildings and it has to be done in a sustainable way. This thesis focuses on the performance of the building envelope; more precisely thermal performance of walls and super insulation material in the form of vacuum insulation. However, the building envelope is just one part of the whole building system, and super insulators have one major flaw: they are easily adversely affected by other problems in the built environment.  Vacuum Insulation Panels are one fresh addition to the arsenal of insulation materials available to the building industry. They are composite material with a core and an enclosure which, as a composite, can reach thermal conductivities as low as 0.004 W/(mK). However, the exceptional performance relies on the barrier material preventing gas permeation, maintaining a near vacuum into the core and a minimized thermal bridge effect from the wrapping of barrier material round the edge of a panel. A serpentine edge is proposed to decrease the heat loss at the edge. Modeling and testing shows a reduction of 60% if a reasonable serpentine edge is used. A diffusion model of permeation through multilayered barrier films with metallization coatings was developed to predict ultimate service life. The model combines numerical calculations with analytical field theory allowing for more precise determination than current models. The results using the proposed model indicate that it is possible to manufacture panels with lifetimes exceeding 50 years with existing manufacturing. Switching from the component scale to the building scale; an approach of integrated testing and modeling is proposed. Four wall types have been tested in a large range of environments with the aim to assess the hygrothermal nature and significance of thermal bridges and air leakages. The test procedure was also examined as a means for a more representative performance indicator than R-value (in USA). The procedure incorporates specific steps exposing the wall to different climate conditions, ranging from cold and dry to hot and humid, with and without a pressure gradient. This study showed that air infiltration alone might decrease the thermal resistance of a residential wall by 15%, more for industrial walls. Results from the research underpin a discussion concerning the importance of a holistic approach to building design if we are to meet the challenge of energy savings and sustainability. Thermal insulation efficiency is a main concept used throughout, and since it measures utilization it is a partial measure of sustainability. It is therefore proposed as a necessary design parameter in addition to a performance indicator when designing building envelopes. The thermal insulation efficiency ranges from below 50% for a wood stud wall poorly designed with incorporated VIP, while an optimized design with VIP placed in an uninterrupted external layer shows an efficiency of 99%, almost perfect. Thermal insulation efficiency reflects the measured wall performance full scale test, thus indicating efficiency under varied environmental loads: heat, moisture and pressure. The building design must be as a system, integrating all the subsystems together to function in concert. New design methodologies must be created along with new, more reliable and comprehensive measuring, testing and integrating procedures. New super insulators are capable of reducing energy usage below zero energy in buildings. It would be a shame to waste them by not taking care of the rest of the system. This thesis details the steps that went into this study and shows how this can be done. / QC 20120228
8

Performance Evaluation of Foamed Warm Mix Asphalt Produced by Water Injection

Ali, Ayman W. 12 August 2013 (has links)
No description available.

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